Shoulder pull dump valve, y/n

[Cajuncru Diver]

As for me I don't try to tell the automotive engineers how to design my anti-lock brakes, I just use them in the manner they designed them, I don't tell the aeronautical engineers how to design the variable pitch prop, just use it in the manner it was designed, likewise I don't try to redesign the BC dump systems, just use them as designed. IMHO if it wasn't safe it wouldn't ever make it to much less remain on the market.

 

[TSandM]

Well, you have just had a good introduction into the value of standardized equipment!

I'm a little confused, though, about the incident you describe. Are you sure the problem was with your wing? You keeping writing "DS", which to me says dry suit. Dry suits are NOTORIOUS for causing buoyancy problems, because the air bubble has to be moved around to be vented, and the vents tend to be slow. If you initiated an uncontrolled ascent for any reason and were not able to vent the drysuit, you were headed for the surface no matter WHAT you did with a dump valve on your wing. (I speak from scary personal experience here.)

But if you always dive with the same group of people, there is value in having your equipment the same. As much as I hate to recommend a piece of equipment I don't believe is necessary or beneficial, it's important that your buddies be able to operate your stuff in an emergency.

 

[Nemrod]

sounds like a lot of swimming to me I prefer to float along neutral, which is impossible without some air in bc/wing until end of dive.

Feet first starts are common if you start the dive positively buoyant and talking with buddy. Unless there is a great need to get down quickly(currents usually) I prefer to start the dive positive and when ready to descend I dump from pull dump on inflator till I get a bit neg and then go horizontal for rest of descent and most of rest of dive using rear dump. I agree that once you get under the water you need to get either horizontal or head down and not drop to bottom feet first, vis around here would usuall have your feet hitting bottom before you could see in that position . I also usually stay horizontal on ascent till past safety stop, maybe all the way to surface if in a protected body of water.

Also, I dive with lots of newly certified divers at local watering holes and starting off negative is usually a bad choice and good way to loose that newbie on way down. I only do negative entry's with a regular dive buddy I know is unlikely to have buoyancy, equipment, or ear clearing issues. JMHO,YMMV

Time and time again I have watched divers do feet first descents in 80 feet of water with current, by the time they hit bottom feet/butt first they are in another country. I start negative, do a surface dive (not a pike) and away I go swimming down with my fins propelling me. Don't spend no time floating, we discuss our plans beforehand. Obviously at depth air will be introduced into the BC to compensate for suit compression when wearing heavy exposure protection or other variables to achieve neutral bouyancy. I dump off a little during the dive as my tank is consumed and by the end of the dive I may dump a little more to begin my ascent slightly negative--swimming up. I will vent off on the way up--swimming---as required to maintain a slightly negative to neutral condition. I do not allow the BC to balloon or lift me upward--I swim. Once at my deco/safety stop, I assume a neutral bouyancy or just so slightly negative to help maintain my ceiling (if current and surge etc.) Never do I use the BC to propel me up or down, my fins and legs do that and I orient my body to accomplish that. Once on the surface I may introduce air into the BC if needed to allow me to relax or to swim on my back comfortably if required to do so. Others don't do it that way, whatever works I suppose.
N

 

[Scott M]

Well, you have just had a good introduction into the value of standardized equipment!

I'm a little confused, though, about the incident you describe. Are you sure the problem was with your wing? You keeping writing "DS", which to me says dry suit. Dry suits are NOTORIOUS for causing buoyancy problems, because the air bubble has to be moved around to be vented, and the vents tend to be slow. If you initiated an uncontrolled ascent for any reason and were not able to vent the drysuit, you were headed for the surface no matter WHAT you did with a dump valve on your wing. (I speak from scary personal experience here.)

But if you always dive with the same group of people, there is value in having your equipment the same. As much as I hate to recommend a piece of equipment I don't believe is necessary or beneficial, it's important that your buddies be able to operate your stuff in an emergency.

This was with the dry suit. The incident went like this at least to the best of my memory which in a case like this can be sketchy.

We were diving a small canyon about 40'-45' pretty descent current for the out leg, nice ride back. I had a really good dvie going. Along the route back I started feeling light so I dumped a little air out of the wing. I heard it so I know I dumped. This did not help much and I still felt light so I rolled to me right and vented the DS some, not completely but I could feel it squeeze so I know I dumped some. I am still a little light and starting to ascend like someone is pulling me up by my tank. I patted down my hood as I have had problems with it before capturing air even though it has three vents. It is pretty full of air but it will not dump it so I went a little veritcal and tried to dump my wing again but nothing is coming out so I rolled to my right again and completely dumped the DS, it is definitely dumped because I can feel the squeeze. I am still ascending. This all happened as you can imagine very fast. At this point I motion to my buddy that I am having a problem. He grabs my B/P and dumps all of his air to hold me down but it is not happening. I am vertical at this point and have my inflator above my head trying to dump but nothing is coing out as best I can tell. He pulls it down and tries to pull dump which doesn't work since I don't have one. By this time we are at 20' and nothing to do but go up. At the surface I explained the incident and we decide to try and go back down and see if I can. I raise the inflator and dump and down we go. I must have added air at the surface to stabilize and talk thats why I was able to dump. I am able to complete the dive. No air in my wing and none in my DS but I am still a little light. I assume I was way underweighted but I only had on an MK2 and I was carrying 16lbs of lead, 6 lb SS/Bp and 6 lb sta so total of 28lb using an AL80. I can only assume I was getting light towards the middle of the dive and maybe added instead of dumping.

 

[Teamcasa]

This argument fascinates me. Modern shoulder dumps do have a cord in them that prevent over stretching of the inflator hose. It is virtually the same setup as a rear dump. If you are pulling the hose hard enough to pull it lose then you must have pulled it really hard. The same goes for a rear dump, you just don’t need to pull it that hard.

Like Nemrod, I vent the BC either from the shoulder or hose then do a head first decent. I was never a fan of feet first, It just never seem natural. During the dive I vent from where ever is most comfortable and easy to reach depending on my position and what I’m doing. Sometimes it the rear or the shoulder dump, rarely through the hose.

To obsess of it being a failure point seems a bit extreme to me. If it fails, you have either not checked and serviced it properly or you jerked way to hard. BTW, That’s true for any dump valve.

 

[Gombessa]

As for me I don't try to tell the automotive engineers how to design my anti-lock brakes, I just use them in the manner they designed them, I don't tell the aeronautical engineers how to design the variable pitch prop, just use it in the manner it was designed, likewise I don't try to redesign the BC dump systems, just use them as designed. IMHO if it wasn't safe it wouldn't ever make it to much less remain on the market.

You don't need to tell an engineer how to design something, but you do make a decision as a consumer whether or not you want a sports car or RV, automatic or manual transmission, a sunroof, convertible, or turbocharger, and you live with the benefits and consequences of that choice.

IMHO if it wasn't safe it wouldn't ever make it to much less remain on the market.

I think I have a little less faith than you. With apologies to the riders on the forum, if the above was true, motorcycles would be a thing of the past

 

[Twistedarts]

I don't understand what you are talking about actually. When I SWIM down, descend, I vent air (why is there any air in the wing anyways, I empty mine, suck it flat before I enter the water) from the rear pull dump on my wings because I am swimming down, head first, feet up propelling me downward. When I am horizontal during the "cruise" portion of the dive I vent usually from the rear dump if I accidently hit the inflator to long or over adjust. I do that by rolling to the side and tucking my head down slightly. When I swim up, head first, I vent using the inflator hose and I generally do not need to free it from the D ring bungee to vent effectively, roll that shoulder high if need be. I also pre-dump some of the bubble through the rear dump before beginning my ascent.

A good day is when I never have to put any air, none, NONE, in the wing from beginning to end of the dive. That is a goal. I dive as if I had no BC. I swim down, I swim around and then I swim up, swim is the key.

These feet first decents like I see people doing now often result in them being blown off by current, swim down, swim to the wreck, reef or whatever, no feet first stuff, how can you see where you are going?

N

Sorry Nemrod, let me clarify. most of the time i'm usually at the surface waiting for other divers floating like a cheerio. from there i grab the shoulder dump and start my descent. once under I go horizontal as this (right or wrong) is what I was told to do by padi. I'm glad to see that my natural instinct of swimming down appears to be correct, thank you. nasds was soooo long ago.

 

[newman_diver]

The shoulder dump has 2 issues that lead me to not use them. 1, they have a higher profile than a standard elbow and can get damaged much easier by overhead hazards (wrecks, caves, etc). Secondly, the cable and associated parts inside the inflator tube tend to corrode due to lack of maintenance. It can be difficult to clean these parts without taking the tube apart and in my experience some shops do not inspect these parts during annual service.

I used to use a BCD that had a pull dump, standard dump and an additional shoulder and bottom dump. I have since gone to a wing with a standard dump and a bottom dump. I can dump air in almost any position, I can find both with my eyes closed and it's less to maintain.

Tyler